JP6035792B2 - Backscatter, forward scatter and beam blur correction device, back scatter, forward scatter and beam blur correction method and back scatter, forward scatter and beam blur correction program - Google Patents

Description

  The present invention takes into account the effects of backscattering, forward scattering, and beam blur when creating a periodic pattern in consideration of the effects of backscattering and beam blurring from the substrate that occur in the drawing process. The present invention relates to a backscatter, forward scatter and beam blur correction apparatus, a backscatter, forward scatter and beam blur correction method, and a backscatter, forward scatter and beam blur correction program.

  Electron beam lithography based on electron beam lithography is mainly used for microfabrication techniques that require high precision and resolution, such as semiconductor photomasks and nanoimprint molds. In semiconductor photomasks, the production of devices by lithography (EUV lithography) using EUV (Extreme Ultra Violet) with a shorter wavelength is being studied with the miniaturization of LSI. The original EUV mask is required to have a finer pattern, and pattern formation faithful to the design dimensions is required. Further, in the mold for nanoimprint, it is necessary to form a fine pattern in a large area with high accuracy.

  In the electron beam lithography drawing process, a mask pattern is drawn on a resist film formed on a substrate, developed, and a resist pattern is formed. The electron beam irradiated on the resist is elastically scattered and spreads within the resist and the substrate. It is known that it affects areas other than the drawing figure. Due to this effect, the area surrounding the drawing figure that is covered with the spread of the electron beam is equivalent to drawing with overdose (exposure amount greater than the set value), and the deviation from the design dimension is Arise. There are two types of spread due to electron beam scattering. One is forward scattering with an electron beam incident and elastically scattered while passing through the resist, and has a high energy with a radius of several nanometers, and the other is an electron that has passed through the resist. Is a backscattering that spreads in a wider range than the forward scattering and has a low energy due to elastic scattering in the substrate and reentering the resist. The main cause of the phenomenon affecting the periphery of the drawing figure is the spread of the electron beam due to backscattering, and various correction methods have been considered in order to reduce the deviation of the pattern dimension due to this influence.

  The range affected by the backscattering is a wide range having a radius of about 10 μm or more when drawn with an electron beam having a high acceleration voltage of 50 keV or more. Moreover, it is known that in an area within a radius of about 10 μm, the increase in exposure due to backscattering is not dependent on the pattern figure, but is made uniform based on the pattern area density in the unit section.

  As a method for correcting backscattering, there are a representative figure method and an area density map method. In the representative graphic method, taking advantage of the characteristics of the backscattering described above, the design of the drawing pattern is divided into unit sections of a certain size, and one or more figures in the unit section are equal to the total figure area in the unit section, In addition, correction is performed by replacing it with one rectangular figure located at the area center of gravity.

  In addition, in the area density map method, the unit partition is bitmap-developed, the pattern area density of the pattern figure in the unit partition is calculated, and an averaging process is performed to average the pattern area density between adjacent unit partitions. Perform backscatter correction.

  Also, when drawing a design that includes a pattern with periodicity over a wide range, if the entire drawing pattern is divided into unit sections and the gradient of the pattern area density change between adjacent unit sections is large, the unit section is divided into multiple areas. A method is considered in which a different correction amount is applied to each region. (See Patent Document 1).

  While back scattering affects a wide range, it is known that forward scattering and beam blur (Beam Blur) affect a narrow range and cause a shift in pattern dimensions. Typical examples of electron beam drawing methods are spot beam electron beam drawing and variable-shaped electron beam drawing, but neither can irradiate an electron beam with a uniform current density. Spreads and beam blur occurs. When the patterns are adjacent to each other, the beam irradiated to the resist spreads by this beam blur, and affects the adjacent patterns. As a result, the target pattern dimension cannot be obtained. Similar to the beam blur, the forward scattering is also a factor that adjacent patterns influence each other and the target dimension cannot be obtained.

  With the miniaturization of the pattern to be drawn, the distance between patterns is becoming shorter. The spread of beam blur and forward scattering is several nanometers to several tens of nanometers, and the patterns within the extent of the influence affect each other, and the same phenomenon as the exposure more than the exposure required for the target pattern dimensions As a result, the pattern size tends to increase or decrease.

  In the case of electron beam drawing of a fine pattern, a method of sizing pattern data in advance is known. If the pattern dimension can be predicted to be smaller than the target dimension, the pattern data after lithography is brought closer to the target value by correcting the pattern data to a dimension larger than the target.

JP 2009-295893 A

  In the above-mentioned representative graphic method, graphic map method, and graphic map development method, the drawing pattern is averaged in the unit section or replaced with a rectangle, so the blur, forward scatter, and back scatter that affect each pattern individually. Therefore, the deviation from the target value of the pattern dimension cannot be corrected.

  In the method of dividing the unit section into a plurality of regions, it is possible to finely apply the backscatter correction value, but it is not possible to reduce the influence of beam blur and forward scattering.

  In the sizing method described above, prior drawing or the like is necessary to calculate and optimize an appropriate sizing amount, which requires high technology, time, and cost. In addition, the size of backscattering on the periphery changes by applying sizing. In response to this change, it is necessary to size the surrounding pattern design. As described above, it is difficult to perform sizing on the pattern data in consideration of the influence of back scattering while considering the influence of beam blur and forward scattering.

  The present invention solves the above-described problem, and calculates an optimal exposure condition considering the influence of backscattering, forward scattering, and beam blur when a pattern having periodicity in a large area is drawn with an electron beam. it can. By creating a pattern based on this, it is possible to reduce the influence of backscattering, forward scattering and beam blur, and to reduce the deviation between the resist pattern size and the target design pattern size. It is an object of the present invention to provide a scatter, forward scatter and beam blur correction apparatus, a back scatter, forward scatter and beam blur correction method, and a back scatter, forward scatter and beam blur correction program.

  While high-precision and high-resolution fine patterns are required, it is required to simultaneously correct the backscattering and the effects of forward scattering and beam blur. That is, it is necessary to perform correction by simultaneously considering each pattern of several tens of nm to several hundreds of nm, backscattering spreading over a large area of 10 μm or more, and different scales. Although the number of patterns is increasing with miniaturization, it is necessary to calculate optimum exposure conditions for all patterns without taking time.

  The present invention is for forming a pattern having periodicity over a large area, such as a part of a semiconductor or a photomask for a semiconductor, a nanoimprint mold, an optical-related element, or a biochip, with high accuracy and high resolution. This is for easily calculating the exposure amount correction value.

In view of the above-described problems, the backscattering, forward scattering, and beam blur correction device according to the present invention occurs during the drawing related to electron beam lithography that draws and develops a pattern design on a resist film formed on a substrate. In a backscattering, forward scattering and beam blur correction device that reduces the effects of backscattering, forward scattering and beam blur, the pattern design information, the backscatter correction coefficient, the energy threshold used for simulation, and the material information of the workpiece A basic pattern acquisition unit that acquires a basic pattern of a group of periodic patterns that form a pattern design based on the pattern design information input from the input unit, and the basic The pattern information is acquired, and the energy threshold value input from the input unit and the previous Based on the material data of the workpiece, and acquires the area and optimum exposure of FIG type your capital constituting the basic pattern, the optimum exposure amount acquisition unit of FIG shaped your capital area and FIG type your capital, the pattern design Based on the above information, in the periodic pattern constituting the pattern design, a one-cycle pattern including an undrawn portion is acquired, and a one-cycle pattern acquisition unit that acquires an area of one cycle, and the one-cycle area When the area of the diagram form your capital, it obtains an average exposure amount of one period based on the optimum exposure of the view form your capital, and the average exposure amount acquisition unit of one period, and the average exposure amount of information, and information of the view form your capital of optimum exposure amount, based on said backscatter correction factor and the drawing area density to obtain an exposure amount correction value, and exposure correction value acquisition unit of FIG type your capital, the exposure amount based on the optimum exposure of the view form our city and the correction value, To obtain an exposure amount after positive, characterized acquisition unit of the corrected exposure dose, an output unit which outputs the corrected exposure dose along with the pattern design and the basic pattern, in that it comprises.

Said backscatter, the forward scattering and beam blur correction apparatus, the average exposure amount acquisition unit of the one period, the area of at least said one period, and the area of the view form your capital, the optimum exposure of the view form your capital It is calculated by a function based on a quantity.

Said backscatter, the forward scattering and beam blur correction apparatus, the view form your capital of exposure correction value acquisition unit, at least the average exposure amount, and the optimum exposure amount of the view form your capital, from the input unit It is calculated by a function based on the backscattering coefficient representing the magnitude of the input backscattering.

  In the backscattering, forward scattering, and beam blur correction device, the post-correction exposure amount acquisition unit is calculated by a function based on at least the exposure amount correction value and the optimal exposure amount.

In view of the above-described problems, the backscattering, forward scattering, and beam blur correction methods according to the present invention are related to electron beam lithography in which a pattern design is drawn and developed on a resist film formed on a substrate. In the backscattering, forward scattering and beam blur correction method for reducing the effects of backscattering, forward scattering and beam blur, the pattern design information, the backscatter correction coefficient, the energy threshold used for the simulation, and the material information of the workpiece Based on the information on the pattern design input from the input unit, to acquire a basic pattern of a group of patterns having a periodicity constituting the pattern design, to acquire information on the basic pattern, the input Based on the energy threshold value input from the unit and the material information of the workpiece Get the area and optimum exposure of FIG type your capital constituting the basic pattern, based on the information of the pattern design, the periodic pattern constituting the pattern design, to get the one period of the pattern including a non-drawing portion , acquires the area of one period, obtains the area of the one period, and the area of the diagram form our city, the average exposure of one period based on the optimum exposure of the view form your capital, the average exposure of information, and the information of the view form your capital of optimum exposure, on the basis of said backscatter correction coefficient and drawing area density to obtain an exposure amount correction value, the view form your bets for said exposure correction value The corrected exposure amount is acquired based on the optimum exposure amount, and the corrected exposure amount is output together with the basic pattern and the pattern design.

In view of the above problems, a backscattering, forward scattering, and beam blur correction program according to the present invention is generated at the time of drawing related to electron beam lithography for drawing and developing a pattern design on a resist film formed on a substrate. A backscattering, forward scattering and beam blur correction program for reducing the effects of backscattering, forward scattering and beam blur, wherein the pattern design information, backscatter correction coefficient, energy threshold used for simulation, and workpiece material The pattern design is configured based on the pattern design information input from the input unit using an input unit that receives an input of information using an input device and stores the information in a storage device. Basic pattern acquisition means for acquiring a block of basic patterns having periodicity; Using the computing device, the acquired information of the basic pattern, based on the material information of the workpiece and the inputted energy threshold from the input unit, the optimum and area of FIG type your capital constituting the basic pattern to obtain an exposure amount, and the optimum exposure amount acquisition device of FIG type your capital area and FIG type your capital, using the computing device, based on the information of the pattern design, the periodic pattern constituting the pattern design acquires one cycle pattern including a non-drawing unit, 1 acquires the area of the period, the pattern acquisition means 1 cycle, using the computing device, the area of the one period, the view form your bets of the area, and it acquires the average exposure amount of one period based on the optimum exposure of the view form your capital, and the average exposure amount acquiring means 1 cycle, using the computing device, and the average exposure amount of information, FIG form your door of A proper amount of exposure information, based on said backscatter correction coefficient and drawing area density to obtain an exposure amount correction value, by using the exposure correction value acquisition unit of FIG type your capital, the arithmetic unit, the exposure based on the optimum exposure amount correction value and the view form your capital obtains exposure amount after correction, acquisition means of the corrected exposure dose, using the output device, and the corrected exposure dose the basic pattern The computer is caused to execute the function of each of the means for outputting together with the pattern design.

  According to the present invention, when a pattern having periodicity over a large area is drawn with an electron beam, it is possible to calculate an optimum exposure condition in consideration of the effects of backscattering, forward scattering, and beam blur. By creating a pattern based on this, the influence of backscattering, forward scattering, and beam blur can be reduced, and the shift between the resist pattern dimension and the target design pattern dimension can be reduced.

The block diagram which shows embodiment of this invention and shows an example of a structure of a backscattering, forward scattering, and a beam blur correction apparatus. The block diagram which shows embodiment of this invention and represents an example of the partial expansion of a large area drawing part and pattern design The figure which shows embodiment of this invention and represents the range of 1 period which comprises pattern design, and the example of a basic pattern The figure which shows embodiment of this invention and represents the example of a pattern design The figure which shows embodiment of this invention and represents a basic pattern The figure which shows embodiment of this invention and represents the calculation result of the stored energy distribution by simulation The figure which shows embodiment of this invention and shows the basic pattern of FIG. 4, and the range of 1 period The figure which shows embodiment of this invention and represents the relationship between the drawing area density based on a backscattering correction coefficient, and exposure amount correction | amendment The figure which shows embodiment of this invention and represents the comparison of the stored energy distribution when applying the exposure amount after a conventional method and correction | amendment. The figure which shows embodiment of this invention and represents the example of a pattern design The figure which shows embodiment of this invention and represents the example of a pattern design The figure which shows embodiment of this invention and represents the comparison of the stored energy distribution when applying the exposure amount after a conventional method and correction | amendment. The figure which shows embodiment of this invention and represents the comparison of the stored energy distribution when applying the exposure amount after a conventional method and correction | amendment. The figure which shows embodiment of this invention and represents the comparison of the difference of a resist shape and a design dimension when a conventional method and the exposure amount after correction | amendment are applied for every figure. The figure which shows embodiment of this invention and is a figure showing the comparison of the sum total of the difference of a resist shape and a design dimension when a conventional method and the exposure amount after correction | amendment are applied

Hereinafter, a backscattering, forward scattering and beam blur correction system 100 according to an embodiment of the present invention will be described with reference to FIG. FIG. 1 is a schematic block diagram showing the configuration of a backscattering, forward scattering, and beam blur correction system 100 according to this embodiment. As shown in FIG. 1, the backscattering, forward scattering, and beam blur correction apparatus 100 includes an input unit (input unit) 101, a storage unit (storage device) 102, and a basic pattern acquisition unit ( a basic pattern acquiring means) 103, the area of each figure _{S n (n = 1,2, ··} ) and optimum exposure alpha _n (n = 1, 2, the area of each acquisition unit (figure · ·) S _n And an optimum exposure amount α _n acquisition unit) 104, one cycle pattern acquisition unit (one cycle pattern acquisition unit) 105, and one cycle average exposure amount D acquisition unit (period average exposure amount D acquisition unit). ) 106, exposure amount correction value β _n (n = 1, 2,...) Acquisition unit (exposure amount correction value β _n acquisition unit) 107 for each graphic, and corrected exposure amount α ′ _n (n for each graphic) = 1, 2,... Acquisition unit (post-correction exposure amount α ′ _n acquisition unit) 108 and output unit (output unit) Stage) 109.

  The backscatter correction apparatus 100 has a computer configuration, and relates to electron beam lithography that draws and develops a pattern on a resist film formed on the substrate. Each of the above components is configured in cooperation with a backscattering, forward scattering, and beam blur correction program that reduces the effects of scattering and beam blur. Note that the backscattering, forward scattering, and beam blur correction apparatus 100 may be configured only by hardware such as a dedicated LSI.

  The backscattering, forward scattering, and beam blur correction apparatus 100 uses a backscattering correction coefficient (drawing correction value based on the drawing area density) η that depends on the characteristics of the resist obtained in advance to draw a pattern design. The optimum exposure condition for each pattern is determined.

In the present embodiment, an example in which the backscattering, forward scattering, and beam blur correction apparatus 100 obtains and uses the optimum exposure amount α _n using simulation will be described, but this research is not limited to this. For example, a resist pattern may be actually formed by electron beam lithography, and the optimum exposure amount α _n may be determined from the result. In the present embodiment, the numerical values and parameters used for numerical calculation are examples of the minimum necessary elements, and the optimal exposure amount α _n and the correction value β _n are obtained using other elements. Also good.

  The input unit 101 receives input of information used by the backscattering, forward scattering, and beam blur correction apparatus 100 and stores the information in the storage unit 102. The input unit 101 receives information on a pattern design to be drawn. The input unit 101 includes a transmission / reception interface for receiving transmission data from the outside of the backscattering, forward scattering, and beam blur correction apparatus 100, an input interface for inputting data from an external storage device, a display, a keyboard, a mouse, a tablet, and the like. It can be configured using an input device such as the man-machine interface used.

In addition to the pattern design information, the input unit 101 acquires information on the backscatter correction coefficient η based on the drawing area density and the optimum exposure amount α _n necessary for the calculation performed by the exposure amount correction value β _n acquisition unit 107. An energy threshold value Eth necessary for calculation performed by the unit 104 and substance information of a workpiece such as a substrate material and a resist material are input. Details of these will be described later. The storage unit 102 stores information input from the input unit 101. The storage unit 102 stores pattern design information, backscatter correction coefficient η information, and energy threshold Eth information input from the input unit 101. The storage unit 102 can be configured using a storage device such as a RAM, a flash memory storage device, a magnetic disk storage device, and an optical disk storage device.

In the block basic pattern acquisition unit 103 in the periodic pattern, it is assumed that the pattern 2 is designed on the entire surface of the large area drawing unit 1 as shown in FIG. 2 based on the pattern design stored in the storage unit 102. As shown in pattern 3 in FIG. 3, a block of basic patterns is acquired, and a number is assigned to each figure or shot size constituting the pattern. In the case of FIG. 3, the basic pattern is divided into figures 5, 6, and 7, as shown in FIG. The periodic pattern includes an axis object of the basic pattern and line symmetry. The area of one cycle including the undrawn part must be the same or negligible. Acquired basic pattern is output to the acquisition unit 104 of the optimum exposure alpha _n of each area S _n and the figure of each figure.

The acquisition unit 104 for the area S _n for each graphic and the optimum exposure amount α _n for each graphic acquires information on the basic pattern constituting the periodic pattern acquired by the basic pattern acquisition unit 103. An x direction and a y direction are defined in the resist horizontal direction. Based on the information on the energy threshold value Eth stored in the storage unit 102, the optimum exposure amount α _n is calculated for each figure or shot size constituting the basic pattern. Specifically, the accumulated energy accumulated in the resist when the basic pattern is exposed is calculated based on the information on the substrate material and the resist material stored in the storage unit 102 in the electron beam scattering simulation. From the information of the energy threshold value Eth stored in the storage unit 102, a portion higher than Eth is developed after lithography in the case of a positive resist, and a portion lower than Eth is developed as a portion to be developed in the case of negative resist. The resist shape is predicted. The energy threshold Eth is a parameter specific to the resist, and varies depending on the resist type. Therefore, the energy threshold Eth is obtained in advance through experiments or the like and input to the input unit 101. Since the range delimited by the energy threshold Eth can be expected to be the resist dimension, the exposure amount α _n is adjusted so that the range is the same as the design dimension. When a simulation is performed for each figure and the exposure amount is optimized so that the design dimension is obtained with Eth using the least square method or the like when superimposing, α _n can be easily obtained. In the case of FIG. 3, the figure 5 is obtained as α ₁ , 6 as α ₂ , and 7 as α ₃ . Next, to obtain the area S _n of each figure. In the case of FIG. 3, the area of the figure 5 is obtained as S ₁ , the area of 6 as S ₂ , and the area of 7 as S ₃ . An acquiring unit 106 of the acquired optimum exposure alpha _n and average exposure amount D of the area S _n 1 cycle, and outputs the correction value beta _n acquiring unit 107 of each figure.

  The one-cycle pattern acquisition unit 105 acquires a one-cycle pattern including an unexposed portion from the pattern design stored in the storage unit 102. In the case of the periodic pattern as shown in FIG. 3, the range indicated by the dotted line in FIG. 4 corresponds to the pattern of one period. The area ΔS for one cycle is calculated. The acquired information of the pattern of one cycle is output to the acquisition unit 106 for the average exposure amount D of one cycle.

First obtaining section 106 of the average exposure amount D of the period, using the alpha _n and S _n output from the acquisition unit 104 of the area S _n of each optimum exposure alpha _n and the figure of each figure, the following equation (1 ) To obtain the average exposure dose D. The following formula (1) is generalized and expressed as the following formula (2). I in Expression (2) indicates the number of figures and / or the number of shots. The acquired average exposure amount D is output to the acquisition unit 107 for the correction amount β _n for each figure.

Acquisition unit 107 of the correction amount beta _n of each figure, the output information of the D output from the average exposure amount D acquisition unit 106, the acquisition unit 104 of the area S _n of each optimum exposure αn and the figure of each figure The information on the α _{n and} the information on the backscatter correction coefficient η stored in the storage unit 102 are acquired. The backscattering correction coefficient η is a value specific to the substrate and resist conditions, and must be obtained in advance by simulation or experiment. The correction amount β _n for each figure is a function represented by the optimum exposure amount α _n , the average exposure amount D, and the backscatter correction coefficient η. Here, the following formula (3) is used as a formula suitable for expressing β _n . When the value of α _n is equally uniform for all the figures, the following formula (3) is expressed by the following formula (4), and it can be seen that this is a correction value for a simple drawing area density. A drawing area density σ in a unit area (for example, 10 μm square) larger than one cycle may be introduced into the expression representing β _n . In the case of the following formula (3), it is represented as the following formula (5). In the equation (5), σ is an area density when one cycle is assumed to be a solid pattern, and is used to represent a difference in drawing area density between the central portion and the end portion in large area drawing. σ is obtained from the pattern design stored in the storage unit 102. In the following, it is assumed that σ = 1.

In the correction value α ′ _n acquisition unit 108 for each graphic, information on β _n output from the acquisition unit 107 for the correction amount β _n for each graphic, the optimum exposure amount α _n for each graphic, and the area S _n for each pattern. The information of α _n output from the acquisition unit 104 is acquired. α ′ _n is represented by a function using correction amounts β _n and α _n , and here, the following equation (6) is used as a suitable equation. The correction value α ′ _n calculated by Expression (6) is output to the output unit 109.

The output unit 109 acquires information on the pattern constituting one cycle from the basic pattern acquisition unit 103, acquires the position of the pattern stored in the storage unit 102, and sets the corrected exposure amount α ′ _n for each figure. Output with information. The output unit 109 can be configured using an output device such as an output interface connected to an external computer, a memory, or the like.

By drawing the pattern design stored in the storage unit 102 using the corrected exposure amount α ′ _n for each figure, a desired resist pattern is created in which the influence of backscattering, forward scattering, and beam blur is reduced. be able to.

  In addition, the process of operation | movement of the above-mentioned backscattering, forward scattering, and the beam blur correction apparatus 100 is memorize | stored in the computer-readable recording medium in the format of a program, and when a computer system reads and runs this program, The above processing is performed. Here, the “computer system” includes an arithmetic device such as a CPU and hardware such as various memories, an OS, and peripheral devices. Further, the “computer system” includes a homepage providing environment (or display environment) if a WWW (Internet) environment system is used.

Examples are shown below.
First, a drawing pattern design is input to the input unit 101. The input pattern design is stored in the storage unit 102. FIG. 4 shows the pattern design used in this example. The pattern of FIG. 4 represents a part of large area drawing as shown in FIG. FIG. 4 shows that the pattern design is composed of patterns having periodicity.

Next, the basic pattern acquisition unit 103 acquires a group of basic patterns having periodicity from the design pattern information acquired from the storage unit 102. In the case of the pattern design of FIG. 4, a lump basic pattern as shown in FIG. 5 is obtained. From FIG. 5, the basic pattern is divided into two figures (9) and (10) as shown in FIG. Let (9) be n ₁ and (10) be n ₂ . The information of these basic patterns, and outputs the optimum exposure alpha _n acquiring unit 104 of each area S _n and the figure of each figure.

In optimum dose alpha _n acquiring unit 104 of each area S _n and the figure of each figure, with the simulation to obtain the optimum exposure alpha _n. Although this time simulation is used, the optimum exposure amount α _n may be obtained by experiment and used.

From the information acquired from the basic pattern acquisition unit 103, the dimensions and arrangement of the figures n ₁ and n ₂ and the areas S ₁ and S ₂ are acquired. The dimensions and arrangement of the figures n ₁ and n ₂ are as shown in FIG. 5, and their areas are S1 = 0.02 [μm ² ] and S2 = 0.12 [μm ² ].

Simulation using the information on the dimensions and arrangement of the figure in FIG. 5 above and information on the substrate material, resist conditions such as film thickness and material, exposure conditions, etc., input to the input unit 101 and stored in the storage unit 102 I do. In the simulation, the accumulated energy accumulated in the resist when electron beam exposure is performed is calculated. FIG. 6 shows a simulation result when the figures n ₁ and n ₂ are exposed to 1 [μC / cm ² ] electron beam. The accumulated energy distribution in FIG. 6 represents the energy value in the x direction when the coordinate axis is set in the horizontal direction with respect to the pattern as shown in FIG. The resist is normalized in the depth direction. In the case of a positive type resist, the high energy part is developed, and in the case of a negative type resist, the opposite is true. In this embodiment, a positive resist is used.

Based on the information on the energy threshold Eth input to the input unit 101 and stored in the storage unit 102, the optimum exposure amount α _n is calculated. In the case of a positive type resist, the resist shape after development can be predicted assuming that the portion above the threshold Eth is developed, and the portion below Eth is left with the resist remaining. In this embodiment, Eth = 3.7 × 10 ⁷ [eV / μm ³ ]. Based on the Eth, when the optimum exposure doses α1 and α2 of the figures n ₁ and n ₂ are calculated, α ₁ = 1.62 [μC / cm ² ] and α ₂ = 1.45 [μC / cm ² ], respectively. there were. FIG. 6 shows the accumulated energy distribution when the exposure is performed with the optimum exposure amount. In the portion equal to or higher than Eth, n ₁ is 50 [nm] and n ₂ is 300 [nm]. The information on S ₁ , S ₂ , α ₁ , and α ₂ is output to the correction value β _n acquisition unit 107 and the average exposure amount D acquisition unit 106 for each figure.

Next, the one-cycle pattern acquisition unit 105 acquires a one-cycle pattern based on the pattern design information stored in the storage unit 102. In the case of the pattern design as shown in FIG. 4, one period is expressed as shown in FIG. The size of one cycle is 1 [μm] in the x direction and 1 [μm] in the y direction, and the area ΔS is 1 [μm ² ]. In FIG. 7, one cycle is determined so that the pattern is arranged in the center. However, as long as the distribution of the pattern portion and the undrawn portion is the same as in FIG. 7, the pattern may be arranged anywhere in the range of one cycle. . The information of the pattern of one cycle is output to the average exposure amount D acquisition unit 106.

In averaging the exposure amount D acquisition unit 106, S _1, S ₂ acquired information of one cycle described above, the optimum dose alpha _n acquiring unit 104 of each area S _n and the figure of each figure, alpha _1, alpha _{Based on} the information of ₂ , the average exposure amount D for one cycle is acquired. Equation (2) is used to calculate D. In this embodiment, D is 0.206 [μC / cm ² ]. The acquired D information is output to the correction value β _n acquisition unit 107 for each figure.

The acquisition unit 107 of the correction value beta _n of each figure, the information of the above D, alpha ₁ obtained from the optimum exposure alpha _n acquiring unit 104 of each area S _n and the figure of each figure, and alpha ₂ of the information, The information of the drawing area σ is acquired from the information of the backscatter correction coefficient η input by the input unit 100 and stored in the storage unit 102 and, in some cases, the pattern design information stored in the storage unit 102. Each correction value β _n is acquired. Equation (3) is used to calculate β _n . η is a value depending on the substrate and resist conditions, and in this embodiment, a value of η = 1.15 is used. FIG. 8 shows the relationship between the exposure correction value and the drawing area density when η = 1.15. From FIG. 8, it can be seen that as the drawing surface density increases, the optimum exposure amount suitable for actual drawing decreases. Substituting the above value of η into Equation (3), β ₁ = 0.87 and β ₂ = 0.86 are obtained. The acquired information on β ₁ and β ₂ is output to the acquisition unit 108 for the corrected exposure amount α ′ _n .

In the corrected exposure amount alpha _'n of the acquisition unit 108, beta and _n of information acquired from the acquisition unit 107 of the correction value βn of each figure, the optimum exposure alpha _n acquiring unit 104 of each area S _n and the figure of each figure The corrected exposure amount α ′ _n is acquired from the information of α ₁ and α ₂ acquired from the above. For calculating α ′ _n , Equation (6) is used, and α ′ ₁ = 1.42 [μC / cm ² ] and α ′ ₂ = 1.25 [μC / cm ² ]. Information about the acquired α ′ ₁ and the acquired α ′ ₂ is output to the output unit 109.

FIG. 9 shows the result of creating a stored energy distribution after electron beam exposure by simulation using the corrected exposure amounts α ′ ₁ and α ′ ₂ . The corrected exposure doses α ′ ₁ and α ′ ₂ acquired in the present embodiment were not applied, and the exposure dose corrected by the conventional method (method of exposing all patterns in the unit section with the same exposure dose) was applied. Compare with case results. From FIG. 9, the accumulated energy of n _{1 having} a small graphic area is higher when the corrected exposure amount α ′ ₁ is applied than the conventional method, and the accumulated energy of n _{2 having} a large graphic area is applied the corrected exposure amount α ′ ₂ . You can see that it is lower.

In addition to the pattern designs used in the above embodiments, examples of pattern designs shown in FIGS. 10 and 11 are given. 10 and 11, the basic pattern constituting the pattern design is the same as that shown in FIG. 5, but the area of one cycle is different. In FIG. 10, ΔS is 0.5 [μm ² ]. In this case, ΔS is 0.25 [μm ² ]. 10 and 11, the corrected exposure amount α′n is acquired in accordance with the backscattering, forward scattering, and beam blur correction system 100 shown in FIG. In the pattern design of FIG. 10, α ′ ₁ was 1.26 [μC / cm ² ] and α ′ ₂ was 1.10 [μC / cm ² ]. Further, α ′ ₁ in the pattern design of FIG. 11 was 1.03 [μC / cm ² ], and α ′ ₂ was 0.88 [μC / cm ² ]. Using the acquired α′n, the accumulated energy distribution when pattern exposure is performed by simulation is calculated, and FIGS. 12 and 13 are obtained. From FIG. 12 and FIG. 13, it can be seen that the overall drawing density increases as the area of one cycle becomes smaller, so that the influence from backscattering becomes larger. Similarly to FIG. 9, the accumulated energy of n _{1 having} a small graphic area is higher when the corrected exposure amount α ′ ₁ is applied than the conventional method, and the accumulated energy of n _{2 having} a large graphic area is the corrected exposure amount α ′. _It can be seen that the value of ₂ is lower.

The dimensions of the figures n ₁ and n ₂ are calculated using the energy threshold Eth from the above-described FIGS. 4, 12, and 13 showing the accumulated energy distribution when the corrected exposure amount α ′ _n is applied. Assuming that the difference between the design dimension and the calculated dimension of n ₁ and n ₂ is ΔCD (Critical Dimension), the relationship between ΔCD and the pattern design is expressed in FIG. In FIG. 14, the pattern design of FIG. 4 is represented as P1, FIG. 10 is represented as P2, and FIG. 11 is represented as P3. From FIG. 14, when comparing the exposure amount based on the conventional method and ΔCD when the present embodiment is applied, the dimension of n ₂ is closer to the design dimension of the present embodiment than the conventional method, but the dimension of n ₁ is This embodiment is slightly larger than the conventional method. However, when compared in terms of the total of ΔCD, as shown in FIG. 15, the deviation from the design dimension is larger in the conventional method, and the overall application of the exposure amount α ′ _n is less than the design dimension. The deviation is getting smaller.

  Note that this dimensional shift can be further reduced by adjusting the value of the backscattering correction coefficient η and the application method. Even in the conventional method, it is possible to reduce ΔCD by adjusting η, but it is not possible to reduce the difference between individual pattern shifts, and there is a limit to the improvement of overall ΔCD.

  The present invention can be suitably applied to the production of a pattern having periodicity over a large area, such as a part of a semiconductor or a semiconductor photomask, a nanoimprint mold, an optical-related element, or a biochip.

DESCRIPTION OF SYMBOLS 1 Large area drawing part 2 Drawing pattern 3 Basic pattern 4 The range of 1 period which comprises a drawing pattern 5 The figure 1 which comprises a basic pattern
6 Figure 2 constituting the basic pattern
7 Figure 3 constituting the basic pattern
8 Electron beam drawing unit 9 Graphic n ₁ constituting basic pattern
10 Figure n ₂ constituting the basic pattern
100 Backscattering, forward scattering and beam blur correction device 101 Input unit (input means)
102 Storage unit (storage device)
103 basic pattern acquisition unit (a basic pattern acquisition unit of a periodic pattern, basic pattern acquisition means)
Acquisition of 104 area S _n and the optimal exposure alpha _n (acquisition unit area S _n and the figure for each optimum exposure alpha _n of each figure, the acquisition unit area S _n and the figure for each optimum exposure alpha _n per figure)
105 1-cycle pattern acquisition unit (1-cycle pattern acquisition method)
106 One-period average exposure dose D acquisition unit (means for acquiring one-period average exposure dose D)
Acquisition of the correction value beta _n per 107 graphic (acquisition means of the correction value beta _n of each graphic)
108 corrected exposure amount alpha 'acquisition unit of _n (corrected exposure amount alpha' acquisition means _n)
109 Output unit (output means)
n ₁ optimal exposure amount of the basic pattern of shapes S ₁ figure n ₁ of the area S ₂ figure n ₂ constituting the graphic n ₂ basic pattern constituting the area alpha ₁ figure n ₁ optimal exposure alpha ₂ figure n ₂ alpha ' ₁ exposure D averaged exposure [Delta] S 1 cycle area Eth energy threshold η backscatter correction factor σ drawing area density after the correction of the exposure amount alpha _'2 figure n ₂ the corrected figure n ₁

Claims (6)

Backscattering, forward scattering, and beam blur correction to reduce the effects of backscattering, forward scattering, and beam blur that occur during the drawing related to electron beam lithography that draws and develops a pattern design on a resist film formed on a substrate In the device
Information for the pattern design, a backscatter correction coefficient, an energy threshold used for simulation, and an input unit for inputting material information of the workpiece,
Based on the information on the pattern design input from the input unit, a basic pattern acquisition unit for acquiring a basic pattern of a group of patterns having a periodicity constituting a pattern design;
The acquired information of the basic pattern, based on the material information of the workpiece and the inputted energy threshold from the input unit, acquires the area and optimum exposure of FIG type your capital constituting the basic pattern, FIG. and the optimum exposure amount acquisition unit in the form your capital area and FIG type your capital,
On the basis of the information on the pattern design, in the periodic pattern constituting the pattern design, a one-cycle pattern including an undrawn portion is acquired, and a one-cycle pattern acquisition unit that acquires an area of one cycle;
The area of said one period, and the area of the diagram form your capital, it obtains an average exposure amount of one period based on the optimum exposure of the view form your capital, and the average exposure amount acquisition unit of one period,
The average exposure amount of information, the information of the view form your capital of optimum exposure, based on the drawing area density and said backscatter correction coefficient, to obtain an exposure amount correction value, shape your capital of exposure correction A value acquisition unit;
Based on the optimum exposure of the view form our city and the exposure correction value, obtains the exposure amount after correction, and the acquisition unit of the corrected exposure dose,
An output unit for outputting the corrected exposure amount together with the basic pattern and the pattern design;
A backscattering, forward scattering and beam blur correction apparatus comprising: According average exposure amount acquisition unit of the one cycle, to the area of at least said one period, and the area of the diagram form your capital, characterized in that it is calculated by a function based on the optimum exposure of the view form your capital Item 2. The backscattering, forward scattering, and beam blur correction device according to item 1. FIG form your capital of exposure correction value acquisition unit, at least the average exposure amount, the backscattering coefficient representing the optimum exposure of the view form our city, the magnitude of backscatter is input from the input unit The backscattering, forward scattering, and beam blur correction device according to claim 1, wherein the backscattering, forward scattering, and beam blur correction device are calculated by a function based on   2. The backscattering, forward scattering, and beam blur correction device according to claim 1, wherein the post-correction exposure amount acquisition unit is calculated by a function based on at least the exposure amount correction value and the optimum exposure amount. Backscattering, forward scattering, and beam blur correction to reduce the effects of backscattering, forward scattering, and beam blur that occur during the drawing related to electron beam lithography that draws and develops a pattern design on a resist film formed on a substrate In the method
Input the pattern design information, backscatter correction coefficient, energy threshold used for simulation and material information of the workpiece,
Based on the pattern design information input from the input unit, to obtain a basic pattern of a group of patterns having periodicity constituting the pattern design,
The acquired information of the basic pattern, based on the material information of the workpiece and the inputted energy threshold from the input unit, acquires the area and optimum exposure of FIG type your capital constituting the basic pattern,
Based on the information on the pattern design, in the periodic pattern constituting the pattern design, obtain a pattern of one cycle including an undrawn portion, obtain an area of one cycle,
Gets the area of the one period, and the area of the diagram form our city, the average exposure of one period based on the optimum exposure of the view form your capital,
The average exposure amount of information, the information of the view form your capital of optimum exposure, based on the drawing area density and the backscatter correction factor to obtain an exposure amount correction value,
Based on the optimum exposure of the view form our city and the exposure correction value, obtains the exposure amount after correction,
A backscattering, forward scattering, and beam blur correction method, wherein the corrected exposure amount is output together with the basic pattern and the pattern design. Backscattering, forward scattering, and beam blur correction to reduce the effects of backscattering, forward scattering, and beam blur that occur during the drawing related to electron beam lithography that draws and develops a pattern design on a resist film formed on a substrate A program,
Input means for receiving the pattern design information, backscatter correction coefficient, energy threshold used for simulation, and material information of the workpiece using an input device and storing them in a storage device;
Using a computing device, based on the pattern design information input from the input unit, basic pattern acquisition means for acquiring a block of basic patterns having periodicity constituting the pattern design;
Using the computing device, the acquired information of the basic pattern, based on the material information of the workpiece and the inputted energy threshold from the input unit, the optimum and area of FIG type your capital constituting the basic pattern to obtain an exposure amount, and the optimum exposure amount acquisition device of FIG type your capital area and FIG type your capital,
Using the arithmetic device, based on the pattern design information, in the periodic pattern constituting the pattern design, a one-cycle pattern including an undrawn portion is acquired, and an area of one cycle is acquired. Pattern acquisition means;
Using the computing device, the area of the one period, and the area of the diagram form your capital, and acquires the average exposure amount of one period based on the optimum exposure of the view form your capital, the average exposure of 1 cycle A quantity acquisition means;
Using the computing device, and the average exposure amount of information, the information of the view form your capital of optimum exposure, based on the drawing area density and the backscatter correction coefficient, to obtain an exposure amount correction value, Fig. and the exposure amount correction value acquisition means in the form your city,
Using the computing device, based on the optimum exposure of the view form our city and the exposure correction value, obtains the exposure amount after correction, acquisition means of the corrected exposure dose,
Using an output device, output means for outputting the corrected exposure amount together with the basic pattern and the pattern design;
A backscattering, forward scattering and beam blur correction program for causing a computer to execute the function of each means.

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